Acorn System 1

Acorn Computers was one of the bright stars in British IT in the 1980s, but faded with the onslaught of IBM PC compatibles. Uniquely, it had one ace up its sleeve — the ARM chip architecture, which has gone on to take over the mobile world. Follow the rise, fall and rise again of this unique Cambridge institution, courtesy of the National Museum of Computing's collection at Bletchley Park.

Acorn's first product was the Acorn System 1, based on an automated cow feeder designed by Sophie (nee Roger) Wilson as part of her degree course at Cambridge in 1977. The System 1 (pictured) took shape over the summer of 1978, and Acorn Computers Ltd was formed in November that year in order to sell it.

Built on two standard Eurocard-sized boards, the System 1 had a 1MHz 6502 processor, 1,152 bytes of RAM, 512 bytes of ROM, a 300bps cassette interface, and it cost £70.

Acorn System 234

Acorn's next systems were all rack-mounted Eurocard systems. They added various combinations of video, memory and floppy disk interfaces to the standard CPU, which was still a 1MHz 6502, but with a larger ROM containing more firmware. Called Acorn Systems 2 through 5, prices varied from £320 to around £2,000. The System 2 was released in 1980, and the System 5 in 1983.

The most interesting was Acorn System 3, which formed the basis for the Acorn Atom, the company's first mass-market computer. The System 3 was also the basic development system within Acorn and hosted most of the hardware and software work on the BBC Micro.

Acorn Atom

Acorn's first home computer, the Atom, came with 2KB of RAM and 8KB of ROM, optional colour graphics, Basic, and a proper keyboard. With a kit price of £120 and a built price of £170, it didn't cost much more than the same keyboard sold as a stand-alone accessory for the earlier rack-based systems. A disk drive, costing twice the price of the computer, was not popular.

Introduced in 1980, the Atom (pictured) lasted until made redundant by the Electron in 1983 — but not before it had been given Acorn's first Econet networking system.

BBC Micro

Originally called the Proton, this 2MHz 6502, 16 to 32KB BBC Microcomputer (pictured) was designed to be sold alongside a BBC TV programme and was thus specified to include lots of interfaces, be very durable and be accessible and powerful to program. Although the higher-specified Model B cost £399, that version outsold the Model A — in total, some 1.5 million were sold.

The system was extremely expandable, with room for extra application or language ROMs, a Tube interface for second processors and general purpose parallel, serial and analogue I/O. It also had Econet networking options and a speech synthesiser that used phonemes recorded by BBC newsreader Kenneth Kendall.

Many BBC Micros are still in use today as process and industrial controllers, thirty years after the design was launched.

Acorn Electron

After the Atom and the Proton, the Electron: we shall say nothing of the awful pun used for a 16032-based co-processor system, the Gluon. The Electron was a cut-down BBC Micro, designed for homes and schools that wanted to concentrate on games or teaching programming.

Most of the circuitry in a Model B was put into one ASIC, code-named Aberdeen. However, space and cost constraints meant that sound, I/O and video were restricted over the original, and the whole system ran more slowly.

The Electron was popular primarily as a gaming computer, although sales were disappointing. Production delays, largely down to the ASIC, meant that it wasn't available in quantity for its intended Christmas 1983 market, and by 1984 it was out of date and lacked the momentum of the other gaming computers. However, a number of interfaces were developed for it, including the Plus 3 floppy drive interface shown here.

Acorn ABC

The Acorn Business Computer was the first sign that even when Acorn could build computers, it had the greatest trouble marketing them.

The Acorn Business Computer (ABC) was a BBC Micro with more memory and a selection of second processors, such as the Z80 or 80286, packaged in a large monitor. Launched after the IBM PC, it's hard at this distance to understand the logic of a computer based on an educational machine, with many incompatible variants, but priced as a business computer.

In fact, the ABC was never really launched at all, and the entire range was cancelled before any were delivered to customers — although one was rebranded as the Cambridge Workstation to appeal to engineers. It didn't.

Acorn Communicator

The Acorn Communicator was a computer with a built-in modem, word processor and spreadsheet, and it was based on the 16-bit 6502 variant, the 65816. It had from 128KB to 512KB of memory, reused the Electron's Aberdeen ASIC, and had no storage devices. Instead, Acorn produced — or was going to produce, it's not clear which — a stand-alone file server that connected via Econet.

The Communicator (pictured) saw few sales. It is reputed to have been used by Pickfords and Italian travel agents as a Prestel/Viewdata terminal for access to early online systems. Nothing came of Acorn's plans to sell it to other companies to badge as the mainstay of early networked office systems.

Acorn Master

In an attempt to prolong the life of the BBC Micro, Acorn repackaged, upgraded and expanded the design with a slightly faster processor, more memory, and a wide variety of configurations, all under the 'Master' brand.

In play from 1986 to 1993 — not bad for an 8-bit computer — the Master line included versions that ran videodisc software, which were at the heart of the Domesday project. Other versions had 80186 co-processors that could run the GEM operating environment.

The last one to make any sort of an impact was the Master Compact, which had a 3.5-inch disk drive, a mouse and Acorn's first GUI. This was sufficiently different from the BBC Micro to exclude it from almost all existing software, and by this point nobody was much interested in developing new software for such an archaic architecture.

Acorn 32016

As esoteric as it gets, this is the 32016 co-processor for the BBC Micro. It was also at the heart of the Cambridge Workstation.

The board was around the 32016, a 32-bit National Semiconductor chip that was a contemporary of the Motorola 68000 but a complete flop in the market. It ran its own firmware called Pandora and an operating environment called Panos. It came with between 1MB and 4MB of memory, and ran at either 6MHz or 10MHz.

The whole system was intended for use by engineers, academics and scientists who needed to crunch numbers, so a small number of computer languages were provided, such as Fortran, C, Pascal and LISP. There is no evidence that total sales exceeded the total number of languages.

BBC Micro

Originally called the Proton, this 2MHz 6502, 16 to 32KB BBC Microcomputer (pictured) was designed to be sold alongside a BBC TV programme and was thus specified to include lots of interfaces, be very durable and be accessible and powerful to program. Although the higher-specified Model B cost £399, that version outsold the Model A — in total, some 1.5 million were sold.

The system was extremely expandable, with room for extra application or language ROMs, a Tube interface for second processors and general purpose parallel, serial and analogue I/O. It also had Econet networking options and a speech synthesiser that used phonemes recorded by BBC newsreader Kenneth Kendall.

Many BBC Micros are still in use today as process and industrial controllers, thirty years after the design was launched.